This invention relates to a switch network system which includes a plurality of switch matrices and to a connection data control system which controls or manages connection data signals used for switching each of the switch matrices.
In such a switch network of the type described, each of the switch matrices has input terminals and output terminals, and the matrices are wired to one another. In each of the switch matrices, the input terminals are connected to the output terminals in accordance with connection data signals under control of a main control unit and a main processing unit. In this event, the connection data signals are memorized into a network memory accessed by the main control unit.
Heretofore, a multi-stage switch of a cross type is disclosed as such a switch network system in an article which is described by CHARLES CLOS in Bell System Technical Journal Vol. 32 No. 2 pp. 406-424 and which is titled "Study of Non-Blocking Switching Networks." Alternatively, a network system of a high order group or a ring network system has been also proposed as such a switch network system in Technical Advisory TA-TSY-000496, Issue 3, August 1990,(Bell Communications Research) titled "SONET Add-Drop Multiplex Equipment (SONET ADM) Generic Criteria for a Unidirectional Path Protection Switched, Self-Healing Ring Implementation". Such a ring network system includes a plurality of switch matrices which are arranged as local stations and which are connected through optical transmission paths.
In any event, each switch matrix is switched by the use of the connection data signals to selectively connect the input terminals to the output terminals. In addition, a connection state of each switch matrix and a connection state of the whole of the switch network are monitored on the basis of the connection data signals.
In this switch network system, no consideration is made at all about extinction or breakage of the connection data signals. Accordingly, communication is disrupted at worst because the connection state is released, when such extinction or breakage occurs in the connection data signals.